NAB : insert into select distinct => when used on null, distinct causes loss of type knowledge - Mailing list pgsql-general
From Frank van Vugt
Subject NAB : insert into select distinct => when used on null, distinct causes loss of type knowledge
Date
Msg-id 200408242316.38155.ftm.van.vugt@foxi.nl
Whole thread Raw
Responses Re: NAB : insert into select distinct => when used on null, distinct causes loss of type knowledge  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Hi,


Not exactly a showstopper, but I noticed this behaviour:

db=# create table f1 (id int, value int);
CREATE TABLE

db=# insert into f1 select 1 as id, null;
INSERT 25456306 1

db=# insert into f1 select distinct 2 as id, null;
ERROR:  column "value" is of type integer but expression is of type text
HINT:  You will need to rewrite or cast the expression.

db=# insert into f1 select distinct on (id) 2 as id, null;
INSERT 25456307 1

So it seems distinct applied to the second column causes it to lose knowledge
on its type.

Does anybody happen to know why ?




--
Best,




Frank.


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